This invention relates broadly to the boring of a hole through the wall of a tube from the inside of the tube outwardly at an angle to a longitudinal axis of the tube. More specifically, this invention relates to apparatus for drilling through an oil or gas well casing at an angle to the longitudinal axis of the casing and into the earth strata surrounding the well casing. More particularly, this invention relates to an improved such drilling apparatus and to a means of transporting, deploying and retrieving the drilling apparatus.
Oil and gas wells are drilled vertically down into the earth strata with the use of rotary drilling equipment. A tube known as a casing is placed down into the well after it is drilled. The casing is usually of made of mild steel and is in the neighborhood of 4.5 inches to 8 inches in external diameter (4 inches in internal diameter and up) and defines the cross-sectional area of the well for transportation of the oil and gas upwardly to the earth surface. However, these vertically extending wells are only useful for removing oil and gas from the terminating downward end of the well. Thus, not all of the oil and gas in the pockets or formations in the surrounding earth strata, at the location of the well depth, can be removed. Therefore, it is necessary to either make additional vertical drillings parallel and close to the first well, which is costly and time consuming, or to provide some means to extend the original well in a radial direction relative to the vertical longitudinal axis of the casing horizontally into the surrounding earth strata.
The most common means for horizontal extension of the well has been to drill angularly through the well casing at a first 45xc2x0 angle for a short distance and then to turn the drill and drill at a second 45xc2x0 angle thereby making a full 90xc2x0 angular or horizontal cut from the vertically extending well. These horizontal drills have proved useful for extending the well horizontally but have proved to be relatively expensive.
Another solution to the problem is disclosed in U.S. Pat. Nos. 5,413,184 and 5,853,056, both of which are hereby incorporated by reference herein as if fully set forth in their entirety. In these patents there is disclosed an apparatus comprising an elbow, a flexible shaft or so-called xe2x80x9cflex cablexe2x80x9d and a ball cutter attached to the end of the flexible shaft. The elbow is positioned in the well casing, and the ball cutter and flexible shaft are passed through the elbow, turning 90xc2x0. A motor rotates the flexible shaft to bore a hole in the well casing and surrounding earth strata with the ball cutter. The flexible shaft and ball cutter are then removed and a flexible tube with a nozzle on the end thereof is passed down the well casing, through the elbow and is directed out of the casing through the hole therein. Water pumped through the flexible tube exits the nozzle at high speed and bores further horizontally into the earth strata.
Prototype testing of the device disclosed in U.S. Pat. Nos. 5,413,184 and 5,853,056 has proven less than satisfactory. In particular, a number of problems plague the device disclosed in U.S. Pat. Nos. 5,413,184 and 5,853,056. For example, the disclosed ball cutter is inefficient at best and ineffective at worst in cutting through the well casing. The inherent spherical geometry of a ball cutter causes it xe2x80x9cwalkxe2x80x9d or xe2x80x9cchatterxe2x80x9d during rotation as it attempts to bore through the well casing which greatly increases the amount of time required to bore through the casing. Ball cutters are best utilized for deburring, and/or cutting a radius in an existing hole or slot for example and are simply not suitable for drilling holes.
Another problem is the torsional flexibility of the flexible shaft or flex cable. Rather than transmitting rotational displacement to the ball cutter at 100% efficiency the flex cable tends to xe2x80x9cwind upxe2x80x9d or exhibit xe2x80x9cbacklash,xe2x80x9d thus reducing the already inefficient cutting efficiency of the ball cutter even more.
Yet another problem is the tendency of the elbow to back away from the hole in the casing during drilling with the ball cutter. Such backing away causes the elbow outlet to become misaligned with the hole in the casing thereby preventing smooth introduction of the nozzle and flexible tube into the hole in the casing.
Still another problem is the large amount of torsional friction generated between the elbow passageway and the flex cable which of course increases the horsepower requirements of the motor required to rotate the flex cable. The addition of balls, separated by springs, to the flex cable, in an effort to alleviate the resistance of the apparatus to being rotated, has not remedied this problem.
A further problem is the closed nature of the apparatus of U.S. Pat. Nos. 5,413,184 and 5,853,056. which prevents its being taken apart, inspected, cleaned and repaired as needed.
The invention of my application Ser. No. 09/643,306 overcomes the deficiencies of the apparatus disclosed in U.S. Pat. Nos. 5,413,184 and 5,853,056. That invention is apparatus for boring a hole from an inside of a tube outwardly perpendicular to a longitudinal axis of the tube. The apparatus comprises a drill shoe having a longitudinal axis and being positionable in the tube, the shoe having an inlet, an outlet perpendicular to the shoe longitudinal axis and a passageway connecting the inlet and outlet, a torsional load transmitting element having no torsional flexibility in relation to its bending flexibility, having a longitudinal axis and being disposed in the passageway, the torsional load transmitting element being movable relative to itself about first and second perpendicular axes both of which are perpendicular to the longitudinal axis of the torsional load transmitting element, a hole saw connected to one end of the torsional load transmitting element and a motor rotatably connected to the other end of the torsional load transmitting element. Rotation of the torsional load transmitting element by the motor rotates the hole saw to bore through the tube from the inside of the tube outwardly perpendicular to the longitudinal axis of the tube.
Further improvements in boring technology are nonetheless desired. For example, the invention of U.S. Pat. Nos. 5,413,184 and 5,853,056 is inefficient and time consuming to operate in that after the cutting tool has bored through the well casing the drilling operation must be interrupted so that the entire drilling apparatus can be retrieved to the earth surface in order to remove the well casing cutting tool and to install the earth strata boring water nozzle. The drilling apparatus must then be lowered back down into the well casing to resume the drilling operation.
The invention includes apparatus for boring a hole from an inside of a casing outwardly at an angle relative to a longitudinal axis of the casing. The apparatus comprises a drill shoe having a longitudinal axis and being positionable in the casing, the shoe having first and second passageways which converge into a third passageway exiting the shoe a torsional load transmitting element and a cutting element connected to one end of the torsional load transmitting element, the torsional load transmitting element and cutting element being positioned in the first passageway during non-use and in the third passageway during use, and a fluid conduit and a nozzle connected to one end of the fluid conduit, the fluid conduit and nozzle being positioned in the second passageway during non-use and in the third passageway during use.
The third passageway may exit the shoe at any desired angle of between 0xc2x0 and 90xc2x0 relative to the longitudinal axis of the drill shoe. The angle may be, for example, 75xc2x0 or 90xc2x0. The apparatus may include an exit insert installable in the shoe to provide variability in the exit angle.
The torsional load transmitting element has a longitudinal axis, and preferably has no torsional flexibility in relation to its bending flexibility and is movable relative to itself about first and second perpendicular axes both of which are perpendicular to the longitudinal axis of the torsional load transmitting element. The torsional load transmitting element may be freely movable relative to itself about the first and second perpendicular axes. The torsional load transmitting element may be pivotable relative to itself about the first and second perpendicular axes. The torsional load transmitting element may be freely pivotable relative to itself about the first and second perpendicular axes.
The cutting element may be a hole saw. The apparatus may further comprise a drill bit connected to the end of the torsional load transmitting element centrally of the hole saw. The drill shoe may be fabricated in halves. The torsional load transmitting element may comprise a plurality of interconnected universal joints. The shoe may include an angled end surface adapted to cooperate with a matingly angled end surface of a drill shoe depth locator for locating the shoe at a selected depth in the casing such that an angular orientation of the shoe relative to the casing is establishable by positioning the depth locating device at an angular orientation relative to the casing.
A drill shoe depth locator for locating a drill shoe at a selected depth in a casing comprises a housing, at least one locking arm pivotally connected to the housing and an actuator for selectively pivoting the arm. The arm is pivotable to and between a retracted non-locking position in the housing and an extended locking position wherein at least a portion of the arm projects out of the housing and is adapted to contact a wall of the casing.
The actuator for selectively pivoting the arm may comprise a firing mechanism which fires a charge that propels the arm to the extended locking position. The firing mechanism may include a chamber adapted to accept a charge cartridge, a gas path between the chamber and the pivoting arm and a firing pin which is selectively activatable to strike the charge cartridge. The housing may include an angled end surface adapted to cooperate with a matingly angled end surface of the drill shoe such that an angular orientation of the drill shoe relative to the casing is establishable by positioning the depth locator at an angular orientation relative to the casing.
A tool for deploying a drill shoe depth locator in the casing comprises a housing, at least one locking arm pivotally connected to the housing and an actuator for selectively pivoting the arm. The arm is pivotable to and between a retracted non-locking position in the housing and an extended locking position wherein at least a portion of the arm projects out of the housing and is adapted to engage a surface of the drilling apparatus depth locator.
The actuator may comprise a rod movable longitudinally relative to the housing which cooperates with a cam surface on the pivoting arm to thereby move the arm.
A tool for retrieving a drill shoe depth locator from a casing comprises a housing, at least one locking arm pivotally connected to the housing and a resilient member normally biasing the locking arm to an extended locking position yet permitting upon application of sufficient force the locking arm to move to a retracted non-locking position. The arm is pivotable to and between the retracted non-locking position in the housing and an extended locking position wherein at least a portion of the arm projects out of the housing and is adapted to engage a surface of the drill shoe depth locator.
A mobile drilling apparatus comprises a wheeled trailer having a trailer bed, a drill shoe, a mast mounted on the trailer bed for suspending therefrom the drill shoe, a first reel rotatably mounted on the trailer bed for paying out and taking up a cable connected to the drill shoe, the cable supported by the mast, a second reel rotatably mounted on the trailer bed for paying out and taking up a first length of tubing which communicates fluid from a fluid source to a fluid motor in the drill shoe, the tubing supported by the mast, and a third reel rotatably mounted on the trailer bed for paying out and taking up a second length of tubing which communicates fluid from a fluid source to a fluid nozzle in the drill shoe, the tubing supported by the mast.
The mast may be pivotally mounted to the trailer bed for pivoting movement to and between an upright operable position and a lowered inoperable position. The mast may be mounted to a work platform and the work platform may be mounted to the trailer bed for movement transverse to a longitudinal axis of the trailer bed. The apparatus may further comprise a catwalk extending the length of the trailer bed on one side thereof and mounted to the trailer bed for pivoting movement to and between an upright inoperable position and a lowered operable position wherein the catwalk extends the width of the trailer bed. The catwalk may include a set of steps secure thereto such that when the catwalk is in the lowered operable position an operator may climb the steps from a ground surface to the trailer bed.
The apparatus may further comprise a motor rotatably driving each of the first, second and third reels, a brake mounted to each of the first, second and third reels, a sensor mounted to each of the first, second and third reels for sensing an angular velocity of each of the first, second and third reels and a controller which controls the brakes in response to signals received from the sensors. The apparatus may further include a sensor mounted on the mast for sensing a depth traversed by the drill shoe.
These and other advantages of the present invention will become more readily apparent during the following detailed description taken in conjunction with the drawings herein, in which: